Identification of anthocyanins in black rice (Oryza sativa L.) by UPLC/Q-TOF-MS and their in vitro and in vivo antioxidant activities

• Anthocyanins in black rice were effectively identified by UPLC/Q-TOF-MS.
• Sambubioside was identified in black rice for the first time.
• Anthocyanins in black rice exhibited excellent in vivo antioxidant activity.

Anthocyanins in different types of black rice are different and their in vivo antioxidant activity is poorly studied. In this study, nine anthocyanins were detected by high performance liquid chromatography (HPLC) and eight of them were identified by ultra performance liquid chromatography/time-of-flight mass spectrometry (UPLC/Q-TOF-MS) in black rice. The in vivo antioxidant activity of the black rice extract containing 41.69% of anthocyanins was determined by the model of KBrO3-induced renal injury in mice. KBrO3 caused serious renal injury, with a significant increase in serum creatinine (14.37 ± 0.27 μg/mL versus 8.80 ± 0.38 μg/mL) and blood urea nitrogen (BUN, 625.56 ± 42.62 mg/L versus 348.49 ± 14.90 mg/L) levels. KBrO3 could also cause oxidative stress in the kidney, with a significant increase in renal xanthine oxidase (XOD), malondialdehyde (MDA) and nitric oxide (NO) levels. Pretreatment with the anthocyanin-rich black rice extract remarkably reduced the levels of serum creatinine and BUN and the levels of renal XOD, MDA and NO. The protective effects were due to the free radical scavenging capacity of the anthocyanins.